Role of point defects on conductivity, magnetism and optical properties in In2O3

In order to assess the effects of point defects including transition metal doping on its electronic structure, the self-consistent band structure of the transparent oxide In₂O₃ (in the Ia₃ structure) has been calculated with oxygen vacancies, oxygen and indium interstitial atoms and several transition metal dopants using density functional theory based first principles calculations. An oxygen vacancy alone does not act as a strong native donor but when combined with interstitial indium and (substitutional) transition metal doping, shallow donor levels close to the conduction band are formed. Spin polarized calculations show measurable magnetism in some of the transition metal doped systems while the dielectric functions indicate whether such systems remain transparent among other things.     

Synthesis of pyridinylpyrrole derivatives via the palladium-catalyzed reaction of acetylpyridines with methyleneaziridines

The reaction of methyleneaziridines with o-, m-, and p-acetylpyridines proceeds very smoothly in the presence of a palladium catalyst, affording the biologically very important o-, m-, and p-pyridinylpyrrole derivatives in good to high yields. Not only ortho, meta, and para, but also related substrates, such as acetyl aromatics and hetarenes, can be used as the starting acetyl derivatives to synthesize related compounds to pyridinylpyrrole derivatives.     

Pairing modulations and phase separation instabilities in Bi2Sr2CaCu2O8 + δ

There is growing evidence that the unconventional spatial inhomogeneities in the doped high-_Tc$T_c$ superconductors are accompanied by the pairing of electrons, subsequent phase transitions and condensation into coherent states. We show that such pairing states can be obtained from phase separation instabilities near level crossings. Conditions for coherent pairing instabilities are examined using exact diagonalization of Hubbard-like pyramid structures under variation of coupling and interaction strengths. We also evaluate the behavior of the energy charge gap in the vicinity of level crossings using a parametrization of coupling to the apical site to represent out-of-plane effects. These results provide a simple microscopic explanation of (correlation induced) supermodulation of the coherent pairing gap observed in scanning tunneling microscopy measurements at atomic scale in Bi₂Sr₂CaCu₂O_8 + δ.     

Synthesis of 1,2,3,4-tetrasubstituted pyrrole derivatives via the palladium-catalyzed reaction of 1,3-diketones with methyleneaziridines

The palladium-catalyzed reaction of 1,3-diketones 2 with methyleneaziridines 1 produced the corresponding 1,2,3,4-tetrasubstituted pyrroles 3 in good to high yields.     

Exact thermodynamics of pairing and charge–spin separation crossovers in small Hubbard nanoclusters

The exact numerical diagonalization and thermodynamics in an ensemble of small Hubbard clusters in the ground state and finite temperatures reveal intriguing insights into the nascent charge and spin pairings, Bose condensation and ferromagnetism in nanoclusters. The phase diagram off half filling strongly suggests the existence of quantum critical points and subsequent transitions from electron pairing into unsaturated and saturated ferromagnetic Mott–Hubbard like insulators, driven by electron repulsion. Rigorous criteria for the existence of quantum critical points and crossover temperatures are formulated. The phase diagram for 2×4$2\times 4$-site clusters illustrates how these features are scaled with cluster size. The phase separation and electron pairing, monitored by a magnetic field and electron doping, surprisingly resemble phase diagrams in the family of doped high-Tc$T_c$ cuprates.     

Iron-catalyzed alkyl-alkyl suzuki-miyaura coupling

Chemoselective Suzuki-Miyaura coupling of primary and secondary alkyl halides is realized by using an iron/Xantphos catalyst. Primary and secondary alkyl bromides undergo the reaction to give the coupling products in good yields. Application to the synthesis of long-chain fatty acid derivatives is also described.